For classes that only have static methods, consider making them utility classes. 
Note that this doesn't apply to abstract classes, since their subclasses may well include non-static methods. 
Also, if you want this class to be a utility class, remember to add a private constructor to prevent instantiation. 
(Note, that this use was known before PMD 5.1.0 as UseSingleton).

<p>
This rule is deprecated, use {rule:squid:S1118} instead.
</p>
